1. Field of the Invention
The present invention relates to a semiconductor device.
2. Description of Related Art
Semiconductor devices are used for various purposes. In recent years, semiconductor devices are often used in an apparatus operating with electric power supplied from a battery. Semiconductor devices used in an apparatus with power source from battery are especially desired to consume little power. A technique for suppressing power consumption of a semiconductor device is disclosed in Japanese Unexamined Patent Application Publication No. 2004-186666, for example. Such technique aims to reduce the power consumption of a semiconductor device by suspending to supply power to non-operating circuits among circuits in the semiconductor device.
Inventor has now discovered that there are following problems in the conventional technique. FIG. 1 is a diagram for explaining the conventional technique. In FIG. 1, in a circuit area 2 inside a semiconductor 100, operations can be suspended for a predetermined period of time. In the period to enable to suspend the operations in the circuit area 2, a power supply control circuit (not shown) inside the semiconductor device 100 sends a control signal SLP to a switch SW1 so as to suspend supplying power from a power supply line VDD to the circuit area 2. This prevents leak current or the like from generating that is caused by transistors (not shown) in the circuit area 2, thereby reducing the power consumption of the semiconductor device. However communications between gates G1 and G2 interposing the circuit area 2 may be required even while the power supply to the circuit area 2 is suspended. Specifically, if a repeater circuit (interchange circuit) 30 for relaying a signal S from the gate G1 to the gate G2 is disposed in the circuit area 2, the repeater circuit 30 does not operate while the switch SW1 is in off state. Therefore, in the period when the power supply to the circuit area 2 is suspended, the signal S cannot be communicated between the gates G1 and G2 that are disposed interposing the circuit area 2 therebetween.
To avoid such problem, as shown in FIG. 2, there is a technique to bypass the circuit area 2 to dispose the repeater circuit 3. However wiring must be routed long way, causing signals to be delayed and complicate the adjustment of timings.